CV Stimulants Flashcards by Barrett Thompson

Epinephrine (E)
• Receptors
• Effects
• Uses

Epinephrine

Receptors:
• alpha1=alpha2; ß1=ß2

Effects:
• Binds BOTH beta and alpha to cause HTN and rapid HR (respectively)

Uses:
• Anaphylaxis
• Cadiac Arrest
• Hypotension

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Norepinephrine (NE)
• Receptors
• Effects
• Uses

Norepinephrine

Receptors:
• alpha1 > alpha2 > ß1

Effects:
• binds alpha mainly so you only get HTN

Uses:
• Hypotension (DECREASES RENAL PERFUSION)

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Dopamine (DA)
• Receptors
• Effects
• Uses

Dopamine

Receptors:
D1=D2 > ß > alpha

Effects:
• binds ß and alpha at HIGH CONC. causing Rapid HR and HTN (respectively)

Uses:
• Unstable Bradycardia, Heart Failure, Shock
• Chronotropic Effects predominate at high Dose

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Dobutamine
• Receptors
• Effects
• Uses

Dobutamine

Receptors:
• ß1 > ß2, alpha

Effect:
• Binds ß and alpha to cause Rapid HR and HTN (respectively)

Uses:
• Heart Failure (inotropic > chronotropic)
• Stress Tests

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Isoproterenol [Isuprel]
• Receptors
• Effects
• Uses

Isoproterenol

Receptors:
• ß1 = ß2

Effect:
• Binds ß to cause rapid HR

Uses:
• Electrophysiologic Evaluation of Tachyarrythmia
• Can worsen ischemia

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Phenylephrine
• Receptors
• Effects
• Uses

Phenylephrine

Receptors:
• alpha1 > alpha 2

Effect:
• Binds alpha to cause HTN

Uses:
• Hypotension

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Ephedrine [Pretz-D]
• Receptors
• Effects
• Uses

Ephedrine

Receptors:
• alpha 1 > alpha2 > ß1

Effect:
• INDIRECT activation of alpha and beta cause HTN and increased HR (respectively)

Uses: 
• Hypotension of anesthesia
• Narcolepsy
• Nasal Congestion
• Asthma
• Bronchospasm

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What is the effect of stimulating Beta-1 receptors?

• where are these found?

Location: Primarily found in Cardiovascular System

Effect: Accelerate Heart Rate and Increase the force of contraction

Uses:

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What is the effect of stimulating Beta-2 receptors?

• where are these found?

Location: Beta-2 found in Skeletal muscle (also they are found in CV system with Beta-1 receptors)

Effect: stimulation leads to muscle relaxation and increased perfusion

Uses:

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What is the difference in Direct-acting and Indirect acting Sympathomimetic Drugs?

Direct:
• acts on the POST-Synaptic membrane to stimulate the receptor Directly

Indirect:
• Increase Availability of NE (norepinephrine) and E (epinephrine) by acting on the PRE-SYNAPIC neuron

Mixed:
• Direct activation on Post-synaptic and stimulation of Neurotransmitter release from PRE-synaptic neuron

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In what ways can drugs indirectly act on neurons?

Releasing or Displacing NE
Blocking NE transport into sympathetic neurons
Blocking metabolizing enzymes (Monamine oxidase, MAO) or catechol-O-methyltransferase (COMT)

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What effect does reserpine on:
• Direct-acting drugs
• Indirectly-acting drugs
• Mixed-acting drugs

Direct-acting:
• NO response reduction
• May INCREASE (why?)

Indirectly-acting:
• ABOLISHED responses because there is no NE to stimulate the release of

Mixed:
• Effects will be blunted by reserpine

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What does reserpine do?

• Reserpine depletes NE (norepinephrine) from sympathetic neurons

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Dopamine is dose dependent, what are its effects at the following concetrations:
• Low
• Intermediate
• High

Low:
• D1/D2 receptors predominate

Intermediate:
• Beta receptor actions are seen (tachycardia)

High:
• Alpha receptor actions are seen HTN

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What are the effects of epinephrine?

• are they dose dependent?

***Yes they are dose dependent

Low Dose:
• ß - receptors are predominatly activated
• Increased HR and Decreased Peripheral Resistance (via ß2) WIDEN the Pulse pressure (aka the window between systolic and diastolic)

High Dose:
• alpha - receptors are stimulated

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Explain what happens to the following and why, when NE is injected into someone:
• Peripheral Resistance
• Heart Rate
• BP

Peripheral Resistance:
• Increased - NE acts mostly on alpha-1 receptors to cause vasocontriction

Heart Rate:
• Decreased - reduced by BARORECEPTOR response to increased resistance

Blood Pressure:
• Both Systolic and Diastolic are raised

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Explain what happens to the following and why, when E is injected into someone:
• Peripheral Resistance
• Heart Rate
• BP

Peripheral Resistance:
• Decreased - E acts on Beta-2 receptors mostly at low dose cause vasodilation in skeletal muscle

Heart Rate:
• Increased - E acts on Beta-1 receptors stimulating an increased contraction

Blood Pressure:
• Widened HIGHer SYSTOLIC and LOWER Diastolic

Explain what happens to the following and why, when Isoproterenol is injected into someone:
• Peripheral Resistance
• Heart Rate
• BP

Peripheral Resistance:
• Decreased - E acts on Beta-2 receptors mostly at low dose cause vasodilation in skeletal muscle

Heart Rate:
• Increased - E acts on Beta-1 receptors stimulating an increased contraction

Blood Pressure:
• Widened HIGHer SYSTOLIC and LOWER Diastolic

T or F: Isoproterenol and epinephrine have essentially the same effect on BP.

False, while the effects are similar isoproterenol is much more potent and widens the Systolic/Diastolic window even more because it has NO ALPHA ACTIVITY

Epinephrine
• Routes of Administration
• Adverse Effects
• Uses

Routes of Administration:
• Inhaled, IV, or IM

Adverse Effects:
• Cerebral Hemorrhage
• Ventricular Arrhythmias
• Angina

Treats:
• Hypersensitivity Reactions
• Used at Vasocontrictor w/ Local Anesthetics
• Restores cardiac rhythm in cardiac arrest

Why is epinephrine not given orally or SC if you want systemic effects?

• It vasocontricts really hard so drug cannot travel far

Why is administration of epinephrine often contraindicated with beta blockers?
• what adverse effect might be more likely?

Epinephrine works on both Alpha and Beta receptors

* Vasodilatory effects of beta action helps to prevent insanely high increases in BP caused by alpha action

Epinephrine
• Effect on Heart
• Potential Problems

Heart:
• Directly stimulates ß-1 receptors

Effect:
INCREASED CO (cardiac output)
• High HR (increased SA node depolarization)
• Increased Amplitude of Action Potential
• Increased Rate of Phase 0 depolarization
• Shortens AV node refractory period

Problems:
• Fibrillation (in company of other drugs)
• Pro-arrhythmogenic

How do the effect of NE and E on the SA node differ from that of ACh?
• Why?

NE and E:
• Stimulate increased rates of of SA nodal discharge

ACh:
• Decreased the rate of SA nodal discharge by acting through Muscarinic (M2) receptors

Epinephrine • Effect on Vasculature • Beta-1/2 effects (renal, skeletal mm, coronary) • Alpha Effects (skin)

Overall Sympathetic Effects: Beta-1 /Beta-2 effects: * Beta-1: JGA stimulated => Renin Secretion => renal vascular resistance => Decreased Renal Bloodflow => Na+, K+, Cl- retained * Beta-2: Increased Skeletal Muscle Perfusion, Increased Disastole => Increased Coronary Blood Flow * Both: Increased cardiac output leads to increased Pulmonary Arterial and Venous pressures Alpha Effects: • Decreased Perfusion of the Skin

Why does epinephrine shorten systole?

* Shortened Systole increases the duration of diastole | * Heart is perfused during Diastole

What is the major difference between NE and E when it comes to the heart? • why?

Norepinephrine: • Does NOT increase cardiac output (CO) • NO role in accelerating heart rate - NO BETA-2 action Epinephrine • DOES increase CO • DOES accelerate HR - through BETA-2

What is the difference in NE and E with respect to effects on blood pressure? • why?

• Norepinephrine has a stronger effect on blood pressure because there is no Beta-2 action that acts to dilate blood vessels in the periphery

Adverse effects of Norepinephrine.

Problems: • Fibrillation (in company of other drugs) • Pro-arrhythmogenic • More problems with BP compared to people given E

How is norepinephrine Administered? | • Side effects of administration?

Administration: • IV Side Effects: • Necrosis at infusion side • Diminished Organ Blood Flow

What are the steps in Epinephrine sythesis starting with tyrosine?

Tyrosine => Dopa => Dopamine => Norepinephrine => Epinephrine

Dopamine • Uses/MOA • Administration • Fallbacks?

Uses/MOA: • Acts on D1 receptors in the kidney to INCREASE RENAL PERFUSION => urine output will tell you if its working Administration: • Given IV Drawback: • Can only be given for in patient use because it has a SHORT DURATION OF ACTION and must be given IV

Dopamine | • Dose Dependent Effects

LOW: D1 action • RENAL - Increases Perfusion (inc. GFR) MODERATE: D1 and ß1 action • Increased Cardiac Output (Contractility >> HR) • Increased NE release from Nerve Terminals b/c of Dopamine stimulation HIGH: Alpha action mainly • Increased peripheral Vascular Resistance

Dobutamine • Receptors acted on • Effect • Use

Receptors: • ß1-agonist and Alpha-1 agonsit/antagonist (-/+ enantiomers) • NO ACTIVITY ON DOPAMINE RECEPTORS Effect: • Increased Cardiac Output; Increased stroke volume with minimal effect on heart rate

How does Dobutamine increase stroke volume without affecting heart rate?

* INCREASED myocardial Contractility * DECREASED left ventricular filling pressures * INCREASED urinary output

Dobutamine • Administration • Uses

Administration: • IV infusion • VERY short T1/2 (2min) Uses: • Heart Failure or Acute MI • Post Cardiac Surgery

Isoproterenol: • Receptors • Effect

Receptors: • ONLY ACTS on ß1/2 receptors Effect: • Increased Cardiac Output • Decreased Diastolic BP

Isoproterenol: • Uses • Administration • Side Effects

Uses: • Stimulates HR in pts. with Bradycardia or Heart Block • Used in pts. waiting for Pacemakers Administration: • Parenteral or by aerosol ``` Side Effects: • Palpitations • Tachycardia • Headache • Flushing ```

Phenylephrine • Receptors • Effect

Receptors • Alpha agonist (no ß activity) Effect: • Increased BP by increasing Systemic Arterial Vasoconstriction • Reflex Decrease in BP and CO

Phenylephrine • Uses • Administration • Adverse effects

uses: • Control Hypotension Administration: • SC, IV, IM ``` Adverse Effects: • Angina, Anxiety • Hallucinations • HTN • Insomnia ```

Ephedrine • MOA • Effects • Elimination

MOA: Mixed action • Enhances NE release from sympathetic neurons • Direct agonist of Alpha and Beta Receptors Effects: • Increased HR and CO • Increased BP (due to alpha receptor stimulation in vesssels) Elimination: • Eliminated Unchanged in the Urine

Ephedrine • Uses • Adverse Effects

uses: • Hypotension • Hypotension of Analgesia Adverse Effects: • Increased Cardiac Workload => Angina • Ventricular Dysfunction and Palpitations • Fatal Arrhythmias